Various means have been used in the prior art to eject a canister from a rocket fired or artillery fired projectiles in order to accurately dispense the projectile's warhead cargo accurately over the target area. The canister was generally required to be ejected from the projectile, after the projectile began to slow down in flight, in order to achieve the necessary range. Then the canister had to be opened within one to two tenths of a second, after ejection from the parent munition, in order to maintain flight direction and accuracy in hitting the intended target. The prior art device frequently used electrical, mechanical and/or electrical-mechanical devices to accomplish properly sequenced canister ejection. The problem with these prior art devices was that usually the pressure build up caused by the expulsion charge was so great that it would destroy the electrical, or electromechanical devices thus preventing properly timed activation and release. The above problems are particularly acute in 2-3 inch diameter rockets and 155 mm artillery fired projectile having smoke screening warheads which utilize white phosphorus as a smoke generating agent.